1. Field of the Invention
The present invention relates to an image forming apparatus, and, more particularly, to an image forming apparatus having a structure in which a sheet is inserted between sheets having images formed thereon by an image-forming section.
2. Description of the Related Art
Conventionally, in a copying machine, which is an example of an image forming apparatus, when a stack of originals including a plurality of types of originals (such as color originals and black-and-white originals) are copied, a user can obtain copies of color and black-and-white originals by copying all of the originals using a color copying machine. However, since it takes more time to carry out an image forming operation by a color copying machine than by a black-and-white copying machine, copying black-and-white originals with the color copying machine results in poor image-forming-operation efficiency. Consequently, there is a desire for copying black-and-white originals by a black-and-white copying machine.
To achieve this, color originals and black-and-white originals may be separately copied by copying the color originals with a color copying machine and copying the black-and-white originals with a black-and-white copying machine.
However, when these copying operations are carried out separately, the user must separate the color originals from the black-and-white originals prior to copying them, and, then, put them back into the original order after they have been copied. This is troublesome and time consuming to carry out particularly when the originals are not numbered or when there are many originals.
In order to put back the copies (sheets) from the color copying machine and the copies (sheets) from the black-and-white copying machine into their original order, for example, the copies from the color copying machine must be inserted between the copies from the black-and-white copying machine. The inserting operation is very complicated because it must be carried out by checking the original order of the originals.
Accordingly, the method of separately copying color originals with a color copying machine and black-and-white originals with a black-and-white copying machine has problems in that the operations that the user must carry out are sophisticated and tend to result in mistakes and are troublesome to carry out.
To overcome such problems, a copying machine which comprises a plurality of copying sections (such as a color copying section and a black-and-white copying section) and an inserter, including an inserter tray and a sheet feeder for feeding insertion sheets held by the inserter tray, and which copies various kinds of originals by the aforementioned parts, has been proposed. In general, the inserter tray is provided for supplying sheets that are inserted between sheets having images formed thereon by image-forming sections of the copying sections.
A structure of a copying machine (image-forming apparatus) comprising such an inserter is disclosed in, for example, Japanese Patent Laid-Open No. 2001-171894.
FIG. 7 is a sectional view of the entire structure of such a related copying machine (image-forming apparatus). A copying machine 1000 comprises a reader 101 (original reading means), a printer 102, a sheet processor 103, and an operating panel 40 for, for example, confirming operational settings and setting contents of the printer 102 and the sheet processor 103.
The reader 101 comprises an automatic original feeder 51, a lamp 79, a 3 CCD line sensor 76 (hereinafter referred to as the “CCD 76”) for reading an image, reflective mirrors 72, 73, and 74, and a lens 75. The automatic original feeder 51 sends originals P set on an original setting tray 50 up to an original reading position, reads the originals P at the original reading position, and transports the originals P that have been read to a discharge position. The lamp 79 illuminates the originals P transported to the reading position and set on an original glass 78. The reflective mirrors 72, 73, and 74 guide light reflected from the originals P to the CCD 76. The lens 75 focuses the light reflected from the originals P.
An output signal from the CCD 76 is input to an image signal controlling section 77.
The originals P are set face-up on the original setting tray 50 by a user. The originals P set on the original setting tray 50 are successively read from a topmost original P by the reader 101.
The printer 102 comprises a plurality of sheet holders 53 and 54, and sheet feeders 55 and 56. A plurality of types of sheets S (S1 and S2) of the same size or different sizes can be loaded in the sheet holders 53 and 54. The sheet feeders 55 and 56 feed the sheets S. The sheets S fed from the sheet feeders 55 and 56 are transported to a sheet transportation path 60 through a sheet transportation path 57.
The printer 102 also comprises a laser scanner 61 and an image-forming section 62. Based on image information of an original P read by the reader 101, the laser scanner 61 scans the original P with laser light in order to form a latent image on a photosensitive member 62a. The image-forming section 62 forms a toner image on the photosensitive member 62a and transfers the toner image onto a sheet S to form an image thereon.
The sheet S having the image formed thereon by the image-forming section 62 is transported to a transportation path of the sheet processor 103 by a conveying belt 63, fixing rollers 64, and transportation rollers 65. The toner image on the sheet S is softened and fused and fixed to the sheet S by the fixing rollers 64.
The sheet processor 103 comprises a punching unit 50a, a buffer roller 5, pusher rollers 12, 13, and 14, and first and second change-over flappers 11 and 10. The punching unit 50a punches a hole near the back edge of an insertion sheet I or the sheet S having the image formed thereon. The buffer roller 5 is disposed in the transportation path of the sheet processor 103 and has a relatively large diameter. The pusher rollers 12, 13, and 14 are disposed along the outer periphery of the buffer roller 5 and push the sheet S against the surface of the buffer roller 5 for transporting the sheet S.
The first change-over flapper 11 is used for selectively switching between a non-sort path 35 and a sort path 36. The second change-over flapper 10 is used for switching between a buffer path 23 and the sort path 36. The buffer path 23 is used for temporarily keeping the sheet S or the insertion sheet I.
The sheet processor 103 also comprises transportation rollers 6, first discharge rollers 7, second discharge rollers 9, and a processing tray unit 84. The transportation rollers 6 are disposed at the sort path 36. The processing tray unit 84 comprises a processing tray 82, an aligning plate 88, a lower discharge roller 83b, and an upper discharge roller 83a. At the processing tray 82, the sheet S or the insertion sheet I is temporarily held, is aligned, and is stapled by a stapler unit 80. The aligning plate 88 aligns the sheet S or the insertion sheet I held by the processing tray 82.
The lower discharge roller 83b is secured to the discharge end of the processing tray 82. The upper discharge roller 83a is supported by a swinging guide 81. When the swinging guide 81 reaches its closed position, it presses against the lower discharge roller 83b in order to discharge a stack of sheets S or insertion sheets I onto the processing tray 82.
The first discharge rollers 7 are disposed at the sort path 36 and discharge the sheet S or the insertion sheet I onto a stack tray 86 through the processing tray 82. The second discharge rollers 9 are disposed at the non-sort path 35 and discharge the sheets S or insertion sheets I onto a sample tray 85.
The sheet processor 103 further comprises inserter trays 20, sheet-feed rollers 21, separating rollers 22, and inserters 104A to 104C having the same structures.
Here, an inserting operation refers to supplying the insertion sheets I which are held by the inserter trays 20 of the respective inserters 104A to 104C to the sample tray 85 or the stack tray 86 without passing them through the printer 102 (or by making them bypass the printer 102), and inserting the insertion sheets I between the sheets that are sent to the sheet processor 103 from the printer 102.
Each sheet-feed roller 21 feeds the insertion sheets I, is ordinarily in a waiting state at a position away from the insertion sheets I, and presses against the insertion sheets I when its associated sheet-feed solenoid 111 is turned on at a sheet-feed timing.
The separating rollers 22 separate the insertion sheets I fed from the respective sheet-feed rollers 21. The insertion sheets I separated by the separating rollers 22 are transported by the transportation rollers 23 to 26.
In the copying machine 1000 having such a structure, the user sets the originals P on the original setting tray 50 of the reader 101 or performs a desired setting operation on the copying machine 1000 from the operating unit 40 so as to fetch data from a network, and instructs the starting of an image-forming operation in order to start the image-forming operation.
Next, based on the instruction from the user, at the same time that the reader 101 reads the originals P or the data is fetched from the network, feeding of sheets S from the sheet holders 53 and 54 of the printer 102 is started in order to transport the sheets S to the image-forming section 62 through the sheet-transportation paths 57 and 60. In addition, data required for a sorting operation set by the operating unit 40 and an operation start signal are sent to the sheet processor 103 in order to start operation of the sheet processor 103.
Then, based on the image information read by the reader 101, toner images are transferred onto the sheets S transported to the image-forming section 62, after which the sheets S with the toner images pass between the fixing rollers 64 in order to fix the toner images to the sheets S. After fixing the toner images, the sheets S are transported to the sheet processor 103 and the insertion sheets I are inserted for performing punching, sorting, and stapling operations. By these operations, the insertion sheets I and the sheets S having the respective images formed thereon are set in a predetermined page order.
As mentioned above, the insertion sheets S are set in a face-up state by the user on the inserter trays 20 of their respective inserters 104A to 104C. The set insertion sheets I are successively fed starting from the topmost insertion sheets I by the sheet-feed rollers 21. Then, the insertion sheets I are transported to the sample tray 85 or the stack tray 86 through the transportation rollers 23, 24, and 25, so that the insertion sheets I are in a face-down state when they are discharged.
When, in the printer 102, the sheets S having the respective images formed thereon are sent in a face-down state to the sheet processor 103, after the sheets S have been temporarily sent towards the transportation rollers 66 disposed in a double-sided printing transportation path, the sheets S are reversed and transported to the sheet processor 103. In contrast, when, in the printer 102, the sheets S are sent in a face-up state to the sheet processor 103, the sheets S are transported to the sheet processor 103 without being sent towards the transportation rollers 66, that is, without being reversed.
Therefore, since the sheets S are discharged in a face-down state as described above when carrying out the inserting operation, the orientation of the sheets S is made the same as that of the insertion sheets I by reversing the sheets S and transporting them. Then, the sheets S are transported to the sheet processor 103, and are discharged in a face-down state onto the sample tray 85 or the stack tray 86.
In the copying machine (image-forming apparatus) described above, when the step of forming an image on one surface of a set insertion sheet is added (for example, when a black-and-white table of contents is to be printed on the back of a colored cover sheet), it is necessary to complete the formation of the image on the back of the insertion sheet with a black-and-white copying machine prior to setting the insertion sheet in the inserter.
This means that an additional image-forming step is required, so that there is still room for improving operation efficiency and usability of the copying machine.